Shulkers going through a nether portal without a valid teleportation spot would ignore dimension scaling, and would remain in the coordinates of their previous dimension.

This is not a bug but a feature which has been used for transporting shulkers for many years now.

I do not know how this would be intended. It seems the teleport check fail was made for the same dimension only, not moving between dimensions.

Just because a feature is used for many years without being reported doesn't justify it in my opinion. It should at least respect dimension scaling, but its up to Mojang to decide.

Duplicate of MC-168900 ?

Quasi connectivity is not intended or intuitive but has been used for many years and found many unique applications. Emergent features that weren't intended appear everywhere in this game and generally it's when a feature expands outside the current meta that real innovation can appear.

Plus if you want the dimensions to scale properly then just don't block spaces on the portal, it's easily controlalble and predictable. Why would you intentionally remove a useful feature like this?

Things like quasi connectivity, and how retracting a sticky piston a frame after its extended won't pull blocks are bugs that has been redefined as features because they add unique game mechanics. They allow players to be able to do more things; having access to more game mechanics which open up doors for more creativity, even if its not intended game mechanics.
That's why those bugs are left in while 0 tick farms and TNT dupers are patched out (or will be patched out) instead. Those bugs only let you do things you are already able to do, such as growing sugar cane and other crops, as well as droppers with TNT in flying machines. However, TNT dupers and 0 tick farms accomplishes them MUCH more effectively, and in other words, overpowered, than their intended counterparts. Those bugs do no good for the game, other than making things very unbalanced.
So by that philosophy, this bug does not allow for any new game mechanics, and to be honest, isn't really that useful either. There is not much difference building shulker farms with the nether side 8 times closer to nether spawn. This also makes much more sense too.
And just because there is a method in which to prevent the bug from happening does not justify them. Those bugs are still in the game and still reproducible. The argument "There are procedures you can take to prevent this bug from happening" simply isn't valid because that implies there are methods to reproduce the bugs as well.

No matter what points either side can make in this argument, nobody cares about removing some obscure mechanic which you only discovered browsing through one of ilmango's videos. The bug tracker should not be a tool for people to troll members of the technical community for finding uses for mechanics that were otherwise unknown about and the fact that nobody is voting for this issue simply demonstrates that no one cares.

Chava is right, this ticket is duplicating MC-168900. Hopefully a mod comes soon.

For the record, the fact that something is useful for some technical contraption doesn't imply that it's intended and not a bug. That decision is still up to Mojang.